rculfhash: rename percpu_count to split_count

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/rculfhash.c b/rculfhash.c
index ca63457b7237288a8b7816efef9bed1aa9c2c3a3..e94b9b224422e8e316c5dbeea4be0aff0b002b36 100644 (file)
--- a/rculfhash.c
+++ b/rculfhash.c
@@ -53,7 +53,7 @@
  *   operation.
  * - The resize operation for larger tables (and available through an
  *   API) allows both expanding and shrinking the hash table.
- * - Per-CPU Split-counters are used to keep track of the number of
+ * - Split-counters are used to keep track of the number of
  *   nodes within the hash table for automatic resize triggering.
  * - Resize operation initiated by long chain detection is executed by a
  *   call_rcu thread, which keeps lock-freedom of add and remove.
@@ -173,7 +173,7 @@
 #endif
 
 /*
- * Per-CPU split-counters lazily update the global counter each 1024
+ * Split-counters lazily update the global counter each 1024
  * addition/removal. It automatically keeps track of resize required.
  * We use the bucket length as indicator for need to expand for small
  * tables and machines lacking per-cpu data suppport.
@@ -265,7 +265,7 @@ struct cds_lfht {
        void (*cds_lfht_rcu_unregister_thread)(void);
        pthread_attr_t *resize_attr;    /* Resize threads attributes */
        long count;                     /* global approximate item count */
-       struct ht_items_count *percpu_count;    /* per-cpu item count */
+       struct ht_items_count *split_count;     /* split item count */
 };
 
 struct rcu_resize_work {
@@ -510,72 +510,76 @@ void cds_lfht_resize_lazy_count(struct cds_lfht *ht, unsigned long size,
                                unsigned long count);
 
 static long nr_cpus_mask = -1;
+static long split_count_mask = -1;
+
+static void ht_init_nr_cpus_mask(void)
+{
+       long maxcpus;
+
+       maxcpus = sysconf(_SC_NPROCESSORS_CONF);
+       if (maxcpus <= 0) {
+               nr_cpus_mask = -2;
+               return;
+       }
+       /*
+        * round up number of CPUs to next power of two, so we
+        * can use & for modulo.
+        */
+       maxcpus = 1UL << get_count_order_ulong(maxcpus);
+       nr_cpus_mask = maxcpus - 1;
+}
 
 static
-struct ht_items_count *alloc_per_cpu_items_count(void)
+struct ht_items_count *alloc_split_items_count(void)
 {
        struct ht_items_count *count;
 
-       switch (nr_cpus_mask) {
-       case -2:
-               return NULL;
-       case -1:
-       {
-               long maxcpus;
-
-               maxcpus = sysconf(_SC_NPROCESSORS_CONF);
-               if (maxcpus <= 0) {
-                       nr_cpus_mask = -2;
-                       return NULL;
-               }
-               /*
-                * round up number of CPUs to next power of two, so we
-                * can use & for modulo.
-                */
-               maxcpus = 1UL << get_count_order_ulong(maxcpus);
-               nr_cpus_mask = maxcpus - 1;
-       }
-               /* Fall-through */
-       default:
-               return calloc(nr_cpus_mask + 1, sizeof(*count));
+       if (nr_cpus_mask == -1) {
+               ht_init_nr_cpus_mask();
+               split_count_mask = nr_cpus_mask;
        }
+
+       if (split_count_mask < 0)
+               return NULL;
+       else
+               return calloc(split_count_mask + 1, sizeof(*count));
 }
 
 static
-void free_per_cpu_items_count(struct ht_items_count *count)
+void free_split_items_count(struct ht_items_count *count)
 {
        poison_free(count);
 }
 
 static
-int ht_get_cpu(void)
+int ht_get_split_count_index(void)
 {
        int cpu;
 
-       assert(nr_cpus_mask >= 0);
+       assert(split_count_mask >= 0);
        cpu = sched_getcpu();
        if (unlikely(cpu < 0))
                return cpu;
        else
-               return cpu & nr_cpus_mask;
+               return cpu & split_count_mask;
 }
 
 static
 void ht_count_add(struct cds_lfht *ht, unsigned long size)
 {
-       unsigned long percpu_count;
-       int cpu;
+       unsigned long split_count;
+       int index;
 
-       if (unlikely(!ht->percpu_count))
+       if (unlikely(!ht->split_count))
                return;
-       cpu = ht_get_cpu();
-       if (unlikely(cpu < 0))
+       index = ht_get_split_count_index();
+       if (unlikely(index < 0))
                return;
-       percpu_count = uatomic_add_return(&ht->percpu_count[cpu].add, 1);
-       if (unlikely(!(percpu_count & ((1UL << COUNT_COMMIT_ORDER) - 1)))) {
+       split_count = uatomic_add_return(&ht->split_count[index].add, 1);
+       if (unlikely(!(split_count & ((1UL << COUNT_COMMIT_ORDER) - 1)))) {
                long count;
 
-               dbg_printf("add percpu %lu\n", percpu_count);
+               dbg_printf("add split count %lu\n", split_count);
                count = uatomic_add_return(&ht->count,
                                           1UL << COUNT_COMMIT_ORDER);
                /* If power of 2 */
@@ -592,19 +596,19 @@ void ht_count_add(struct cds_lfht *ht, unsigned long size)
 static
 void ht_count_del(struct cds_lfht *ht, unsigned long size)
 {
-       unsigned long percpu_count;
-       int cpu;
+       unsigned long split_count;
+       int index;
 
-       if (unlikely(!ht->percpu_count))
+       if (unlikely(!ht->split_count))
                return;
-       cpu = ht_get_cpu();
-       if (unlikely(cpu < 0))
+       index = ht_get_split_count_index();
+       if (unlikely(index < 0))
                return;
-       percpu_count = uatomic_add_return(&ht->percpu_count[cpu].del, 1);
-       if (unlikely(!(percpu_count & ((1UL << COUNT_COMMIT_ORDER) - 1)))) {
+       split_count = uatomic_add_return(&ht->split_count[index].del, 1);
+       if (unlikely(!(split_count & ((1UL << COUNT_COMMIT_ORDER) - 1)))) {
                long count;
 
-               dbg_printf("del percpu %lu\n", percpu_count);
+               dbg_printf("del split count %lu\n", split_count);
                count = uatomic_add_return(&ht->count,
                                           -(1UL << COUNT_COMMIT_ORDER));
                /* If power of 2 */
@@ -616,7 +620,7 @@ void ht_count_del(struct cds_lfht *ht, unsigned long size)
                         * Don't shrink table if the number of nodes is below a
                         * certain threshold.
                         */
-                       if (count < (1UL << COUNT_COMMIT_ORDER) * (nr_cpus_mask + 1))
+                       if (count < (1UL << COUNT_COMMIT_ORDER) * (split_count_mask + 1))
                                return;
                        cds_lfht_resize_lazy_count(ht, size,
                                count >> (CHAIN_LEN_TARGET - 1));
@@ -627,15 +631,16 @@ void ht_count_del(struct cds_lfht *ht, unsigned long size)
 #else /* #if defined(HAVE_SCHED_GETCPU) && defined(HAVE_SYSCONF) */
 
 static const long nr_cpus_mask = -2;
+static const long split_count_mask = -2;
 
 static
-struct ht_items_count *alloc_per_cpu_items_count(void)
+struct ht_items_count *alloc_split_items_count(void)
 {
        return NULL;
 }
 
 static
-void free_per_cpu_items_count(struct ht_items_count *count)
+void free_split_items_count(struct ht_items_count *count)
 {
 }
 
@@ -1353,7 +1358,7 @@ struct cds_lfht *_cds_lfht_new(cds_lfht_hash_fct hash_fct,
        ht->cds_lfht_rcu_register_thread = cds_lfht_rcu_register_thread;
        ht->cds_lfht_rcu_unregister_thread = cds_lfht_rcu_unregister_thread;
        ht->resize_attr = attr;
-       ht->percpu_count = alloc_per_cpu_items_count();
+       ht->split_count = alloc_split_items_count();
        /* this mutex should not nest in read-side C.S. */
        pthread_mutex_init(&ht->resize_mutex, NULL);
        ht->flags = flags;
@@ -1606,7 +1611,7 @@ int cds_lfht_destroy(struct cds_lfht *ht, pthread_attr_t **attr)
        ret = cds_lfht_delete_dummy(ht);
        if (ret)
                return ret;
-       free_per_cpu_items_count(ht->percpu_count);
+       free_split_items_count(ht->split_count);
        if (attr)
                *attr = ht->resize_attr;
        poison_free(ht);
@@ -1624,12 +1629,12 @@ void cds_lfht_count_nodes(struct cds_lfht *ht,
        unsigned long nr_dummy = 0;
 
        *approx_before = 0;
-       if (nr_cpus_mask >= 0) {
+       if (split_count_mask >= 0) {
                int i;
 
-               for (i = 0; i < nr_cpus_mask + 1; i++) {
-                       *approx_before += uatomic_read(&ht->percpu_count[i].add);
-                       *approx_before -= uatomic_read(&ht->percpu_count[i].del);
+               for (i = 0; i < split_count_mask + 1; i++) {
+                       *approx_before += uatomic_read(&ht->split_count[i].add);
+                       *approx_before -= uatomic_read(&ht->split_count[i].del);
                }
        }
 
@@ -1654,12 +1659,12 @@ void cds_lfht_count_nodes(struct cds_lfht *ht,
        } while (!is_end(node));
        dbg_printf("number of dummy nodes: %lu\n", nr_dummy);
        *approx_after = 0;
-       if (nr_cpus_mask >= 0) {
+       if (split_count_mask >= 0) {
                int i;
 
-               for (i = 0; i < nr_cpus_mask + 1; i++) {
-                       *approx_after += uatomic_read(&ht->percpu_count[i].add);
-                       *approx_after -= uatomic_read(&ht->percpu_count[i].del);
+               for (i = 0; i < split_count_mask + 1; i++) {
+                       *approx_after += uatomic_read(&ht->split_count[i].add);
+                       *approx_after -= uatomic_read(&ht->split_count[i].del);
                }
        }
 }